Electric signaling transmitter



Nov. '29, 1949 E. M. S. M WHIRTER ET L ELECTRIC SIGNALING TRANSMITTER 3 Sheets-Sheet 1 Filed Aug. 27, 1945 lS-FONSECA,

0 000 0 000 k\ ooooooaa kn: d ldw'l INVENTORS ER/C M 5. McWH/RTER HAROLD N. MDASS HUGH J. WARD. BY R ATTO NEY N GE b m2 238 in NGEQ E I Nov. 29; 1949 E. M. s. McWHlRTER ET AL 2,489,306

ELECTRIC SIGNALING TRANSMITTER 5 Sheets-Sheet 2 Filed Aug. 2'7. 1945 :mEEE

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IN VEN TORS HAROLD N M D7155/5-FON5EC'A TTORNZ Y Nov. 29, 1949 E. M. s. M WHIRTER ET AL 2,439,306

ELECTRIC SIGNALING TRANSMITTER Patented Nov. 29, 1949 UNITED STATES PATENT OFFICE ELECTRIC SIGNALING TRANSMITTER Application August 27, 1945, Serial No. 612,930 In Great Britain July 26, 1944 Section 1, Public Law 690, August 8, 1946 Patent expires July 26, 1964 4 Claims.

This invention relates to electric signalling sys. tems in which signalling is effected by means of impulse trains.

It is an object of the invention to reduce the time required for the transmission of a plurality of impulse trains by eliminating the usual interdigital pause that serves to distinguish one train from the next.

More particularly, it is an object of this invention to provide means at a control station for transmitting to a controlled station a plurality of digital impulse trains of alternate polarity, representative of a desired selective indication, the impulses being preferably arranged according to a constant total code consisting, say, of three digits. These digital impulses may be succeeded, according to a further feature of the invention, by an end of selections impulse of predetermined polarity, followed by a control pulse of prolonged duration, enabling a further selection to be made depending on whether the control pulse is positive or negative.

Additional features and objects will subsequently appear.

The following description relates to the accompanying drawings in which:

Fig. 1 is the relevant circuit at the control station in a remote control and supervisory system;

Fig. 2 is the relevant circuit at the substation in said system; and

Fig. 3 is a time-chart explaining the generation of a signal in the control station circuit.

GENERAL The equipment to be described provides for the selection by the operator at the control station of a particular piece of apparatus, say a circuitbreaker, at the substation, and for the control of the apparatus selected, say by way of closin or tripping a circuit-breaker. Corresponding to each piece of apparatus in the substation there is provided at the control station a selection key PK, a selection indicator lamp PL, and an individual position in the banks of a selection switch PS. When the operator depresses a selection key PK, the appropriate contact is marked in bank PS! of the switch PS, and the switch PS is made to hunt for the contact as marked. When the switch PS finds the marked contact and stops on it, the individual lamp PL lights up. Then when the operator desires to efiect the control of the selected apparatus, assuming that it is a circuit breaker and, therefore, is to be either closed or tripped, he presses either the close key OK or the trip key TK. so that under the control of a send switch CS there is sent out to line Ll, L2, a train of impulses of which the earlier part is distinctive of the particular circuit-breaker, being determined by the setting of switch PS, and of which the later part is distinctive of the control operation desired, being determined by key CK or TK. The selection Signal consists of a constant number of impulses broken up into three digits. For convenience in what follows it will be assumed that the selected circuit-breaker is that which occupies position No. 1'7 on switch PS, and that its three-digit constant-total selection code is 2-4-4.

In the particular embodiment shown and described, use is made of a code havin a constant total of 13 and consisting of three digits, permitting the remote control of twenty different pieces of apparatus. As will be more fully explained hereinafter, the circuit breakers at the substation are divided into two groups of ten units each, the first digit of the code indicating the group and the second the unit selected. The third or complementary digit merely serves as a check on the correctness of the code received. The following table will illustrate this relationship:

Position of Selection Select1on Switch The sending of the signal to line is controlled by the repeated operation and release of relay CSA under the control of an impulsing circuit IG. In Fig. 3 there has been shown by means of a time chart the impulsing of relay CSA and immediately below this is indicated the successive stepping of the send switch CS dependent upon each release of CSA. The impulses may be long or short, positive or negative (positive pulse means positive to Ll, negative to L2) For the sending of a long pulse, relay CD is operated; for a positive pulse relay CP is operated.

The composition of the signal sent to line is shown at the bottom of Fig. 3.

The first digit 2 is sent as two negative pulses, the first of these two being long so as to serve also as a seizure or calling signal at the substation. The second digit, which follows straight on without an inter digital pause, is differentiated from the first by its polarity, the seven impulses being positive. The third digit, again, is differentiated by the fact that its four impulses are negative. There then follows a single positive pulse indicating end of selection; and finally there is the long contro1 or marking out pulse which causes the selected circuit-breaker to be operated. This control pulse is positive for breaker close and negative for breaker trip.

At the substation, negative pulses are received on relay IN and positive pulses on relay IP. The negative trains, that is the first and third digits, are applied to switch RS, which is thus stepped round to a first position in response to the first digit (1. e. position No. 3 in response to digit 2), and to a second position in response to the third digit (1. e. position No. '7 in response to digit "4 following digit 2). According to what said first position is, some one of the switches AS, BS, is selected for the reception of the positive train that constitutes the second digit. Thus at the end of the three-digit selection train one of the switches AS, BS, has been selected and has been set to a position distinctive of a certain circuit breaker. The long control pulse then causes energisation of the appropriate contactor.

DETAILED DESCRIPTION At the control station The selection switch PS, previously referred to, is shown in Pig. 1 as a rotary switch of the nonhoming type comprising the four banks PSI, PS2, PS3 and PS4, as well as a driving magnet PSDM. Each bank is formed by a selected number of contacts of which only the first twenty are shown. The send switch CS, shown as comp-rising four banks CS5, CS2, CS3 and CS5 as well as a driving magnet CSDlVf, is a rotar homing-type selector switch having twenty-five contacts in each bank, shown for convenience in a semi-circular array. It will be understood, however, that in practice the step between contact 25 and home contact l is similar to that between any other pair of adjacent bank contacts.

QPS and QCS indicate the spark quenching circuits for driving magnets PSDM and CSDM, respectively. RSK is a restoring key assumed to be closed at the beginning of a selecting operation.

The symbols and designate positive and negative terminals which may be those of a common battery, not shown. In the following analysis of energLzing circuits for the various relays, specific mention of these terminals has been omitted.

4 Preparing a circuit breaker selection The control operator presses a certain selection key PK particular to a certain breaker, and common relay PD operates: RSK, PK, PD; selection switch PS steps in response to its driving magnet front contact of PD, armature and winding of magnet PSDM until it finds the contact (No. ll) marked by PK in its bank PSi, when it stops; the magnet being held energised: RSK, PK, contact PSHH), wiper PSi, resistor YPS, magnet PSDM. Relay PH operates: RSK, PK, contact PSl(l'l) and wiper PS3, PH, PS; and locks: RSK, front contact (l) of PH, PI-I, PS. Individual lamp PL lights: front contact PH(2), wiper PS2 and contact PSZHl'), PL, indicating that the switch PS stands on that outlet. The operator releases key PK, and relay PD releases.

Sending a seZection and control signal The operator presses close key CK, and relay CR operates: front contact PI-I(3) back contact 02(2) back contact TL( I) normal contact TK( I), CKH) closed, CR; followed by relay TL: same as above through CK(l), front contact CR(I), TL, both CR and TL locking: front contact PEG), back contact CS'(2), front contact TL(I), etc. (Note that the fact of TL having operated renders any further key manipulation ineffective.)

First digit-Jam impnlsesnegative polarity Relay CST operates: lock-out wire, front contact TL(2), Wiper CS2 and contact CSEU), CST. Relay CSA operates impulsively, over an obvious circuit in response to the impulses generated by the 10 i. p. s. generating circuit IG: front contact CS 1G. Switch CS steps once for each impulse: front contact CSAQ), magnet CSDM; relay CD operates on the first operation of CSA: front contact CST(2), wiper CS4 and contact CS LHl), front contact CSAU), CD; and remains operative over a holding circuit, which includes its own front contact (l) and, alternatingly, the back contact (5) of CSA or front contact (l) of the latter in series with bank contacts I to 3, and

wiper CS i, until switch CS reaches position 4, when it releases upon operation of relay CSA. Thus a long negative seize pulse is sent to line, having a duration of 3.50 milliseconds, i. e. for soc m. s. over rront contacts (2) and (Ii) of CD, and. for the last bu m. s. over iront contacts (3) and i) of CSA. Switch CS steps to position 5 on tne fourth release of relay GSA. A short negative pulse is sent to line when relay CSA operates for the fiitn time, oeing of normal length because CD is not energized.

Second digit-seven impaises positive polarity At the end of the second impulse as above described, switch steps to position 6 (note with respect to this position that there is a strapping between contacts CSEGi) and PS3(ll)). Relay CP operates: front contact CS'I(.), wiper CS3 and contact 0533(3), contact PS3(il) and wiper PS3, CP, and locks: front contact CSTQi), back contact of CN, front contact (i) and winding of CP; thus reversing the polarity of the feed to the line Ll, L2: front contacts (3) and t) of CP. The following impulses, seven in all, are therefore of positive polarity, until switch CS reaches position 13 (again be it noted that there is a strapping between contacts CS3(l3) and PS lKlD). Relay CN operates: front contact CST(2), wiper CS3, and contact CS3(i3), contact PSMil'l) and wiper PS4, front contact CP(2), CN, and relay CP releases: at back contact of CN; also CN releases, so that:

Third digitfour impulses-negative polarity The line-signalling feed is restored to negative polarity. Impulse-sending continues until switch CS reaches position 17, where:

End-of-selection-single impalsepositioe polarity Relay CP again operates and looks, so that the impulse sent in this position is positive, and serves to mark the end of the selection code.

Controlsingle pulselong Throughout the movement of switch CS in positions 18 to 24, relay CD is operated and locked thus smothering the impulsing to line at contacts (3) and (4) of relay CSA, and giving one long pulse of 750 milliseconds duration-eight make-periods with seven intervening breakperiods. This is the marketing out or control pulse, and is of positive polarity: CR and CP are operated, CN is de-energized.

Release Switch CS steps to position 25: relay CZ operates: iront contact CST(2), wiper CS3 and contact CS3 (25), OZ. Relays TL and CR release: at back contact CZ(2). Relay CST releases: at contact TL(2), restoring the sending circuit to normal. CS steps to position 1: back contact CST(2), wiper CSI and off-normal contacts CSl(2/2:'i), armature and winding of magnet CSDM. Relay CZ also releases, unless CK is still depressed; in that case CZ remains up and ensures no repetition of the sending until the key is released and for a second time depressed. Key RSK is depressed, relay PH releases, and the selection circuit is restored to normal, extinguishing lamp PL.

Alternative control signal Had it been circuit breaker trip instead of circuit breaker close, the operator would have pressed key TK instead of CK. Then only relay TL would have operated, instead of TL and CR; relay CN would have operated in position 18; front contact CST (2), CS3 wiper and CS3 contact ([8), back contact CRUZ), front contact CP(2), CN; so that relay CP would not have remained energized in positions 18 to 25; and the long single control pulse would have been of negative instead of positive polarity.

OPERATION AT THE SUBSTATION For a complete understanding of the invention, reference is now had to Fig. 2 where the indication receiving mechanism of the controlled station has been illustrated.

Switch RS, which determines the decade or group of the circuit-breaker selected, is shown as comprising two contact banks, RSi and RS2, and a driving magnet RSDM. The unit selection switches AS and RS each comprise five contact banks, ASl to ASS and BSI to BS respectively, and individual driving magnets ASDM and BSDM. Switches RS, AS and BS are of the 25- position homing type and the remarks made in connection with send switch CS (Fig. 1) apply thereto. .QRS, QAS and QBS are respective quenching circuits. IN and IP are polarized relays. C and G are slow-acting relays.

Seize pulse Relay IN operates; relay G operates over front contact (I) of IN, and remains up throughout impulsing; front contact IN( I) or IP( I) G; relay 0 operates: back contact (36(4), front contact G(l C; relay GA operates: front contact (3(2), and home-contacts and wipers of all switches in series, and locks: front contacts GA( I) and G(2).

Polarity discrimination Relays IN and IP respond to the negative and positive pulses, respectively. Switch RS counts negative impulse trains, switch AS or switch BS (according to the setting of RS) counts the positive impulse train.

First digit two impulses-negative polarity Switch magnet RSDM energizes: front contacts GAG), 0(2), IN(Z), armature and winding RSDM; the latter remains operated, because its armature is shunted by front contact GA(2) in series with resistor YRS. Magnet RSDM deenergises: at the end of the impulse, and switch RS steps to position 2. Similarly on the second impulse, switch RS steps to position 3.

Second digit-seven impulsespositive polarity Third digitfoar impnZses-negative polarity These impulses are repeated by relay IN to switch RS, which is thus stepped to position 7. (To check the correctness of the code received, each of the ten individual contacts t through l3 on the RS2 bank is connected in multiple to a corresponding individual contact of bank 3 on all unit selection switches. Note that a strapping exists between contact RSZU) and contacts AS3(I5) and RS305) in parallel.)

Single pulse-end of selection-positive polarity Relay GC operates: front contacts GA(3), 0(3) IP(2) wiper RS2 and contact RS2 (l) contact RS305) and wiper BS3, contact ASS) and wiper A83, GC, and locks: front contacts GA(3), GC(|), GC. (The operating circuit of relay C is now opened at back contact GC(4), but relay 0 continues to hold over back contacts (I) of IN and IP until a long pulse outlasts its slow-release time.)

Control pulse-Zong-pnsitive polarity for breaker close Relay IP operates for 750 milliseconds. Relay C releases. Appropriate close contactor is energised: back contact C(G), front contacts IP(3), GC(2) wiper ASti' and contact AS4( l) wiper BS4 and contact BSMIE). At the end of the long pulse: relay IP releases. Relay Gr slow-releases. Relay GA releases. Relay GC releases. All the selector switches drive home: over back contact GA( I) each via its No. 1 bank and the normal 0 the previous switch. I

7 Alternative-control pulse negative for breaker trip Relay IN operates and relay C releases. The appropriate trip contacto-r is energised: back contact (3(5), front contacts IN(3), GC(3), wiper A85 and contact ASSN), wiper BS and contact Bsilfld), etc. In the table below there is given a compilation of the positions which switches RS, AS and BS occupy upon reception of each selection code, and the order number of the circuit breaker energized thereby. The latter agrees, of course, with the corresponding position of the selection switch PS at the control station as listed in the table given in the description of Fig. 1.

Position 01 Switch Selection Circuit Code Breaker RS AS 13 S l 1 ll 13 3 1 1 1 2 12 5 1 '2 1 3 9 11 7 1 3 1 4 8 10 9 1 4 1 5 7 9 11 1 5 1 6 6 8 13 1 6 1 7 5 7 1 7 1 8 4 6 17 1 8 1 9 3 5 19 1 9 1 10 2 4 21 1 10 2 1 10 13 1 3 11 2 2 9 12 1 5 12 2 3 8 l1 1 7 13 2 4 7 10 1 9 14 2 5 6 9 1 11 15 2 6 5 8 1 13 16 2 7 4 7 1 15 17 2 8 3 6 1 17 18 2 9 2 5 1 l9 l9 2 10 1 4 1 21 2O NOTES Ertenszbzlzty The system is extensible to control any number of switchgear units, each selection switch AS, BS, etc. serving ten such units. In the circuit shown, selection switch AS is used for the ten codes having initial digit 1, BS for the ten codes having initial digit 2, and so on. For each additional selection switch (10 codes) the constant total of the code is increased by one, and the RS positions shown in column 2 of the foregoing table also increase one, corresponding changes being made at the control station.

When the system. is to be thus extended, it will be necess 1 to continue the leads from the RS2 bank, wiper i, and home contacts BS3, BS and BS5 as indicated in Fig. 2. It will he understood, however, that the total check multiple which now includes the leads from contacts l through l3 on the bank will have to be reconnected to a different series of contacts on that bank, consistent with the number of selection switches that have been added. For instance, if two additional unit selection switches are to be used, contacts RS201) and 1232(5) will be connected to be odd terminals of bank 2 of the respective new switches and the total check multiple will then comprise the series of contacts from RS2 6 through RS2 i 5). The conductor which interconnects the even-nun1bered contacts of the A82 and 582 banks will also be extended to the additional selection switches.

The provision of more than two ten-unit selection switches will have the further effect of shortening the marking out or control pulse, at the end of the signal, unless the changes at the control station include an increase in the total number of contacts on send switch CS.

If the coding system is to be extended, other switches similar to PE; may be introduced in which the strapping, as shown on the contacts of PS3, may be arranged for other first digit numbers as necessary, and as outlined above with respect to switches RS and BS.

System guard It will be noted that, as RS is stepped only by the first and third digits of the code, its final position is fixed by the sum of these two digits, or, in other words the constant total minus the sec-- ond digit. Thus there is a definite position oi": RS corresponding to the position. of the selection switch in use, which is fixed by the second digit.

This interrelation of the switches is shown in columns 2, 3 and l of the above table and is used as a check on the correctness of the received code.

Contact spacing The advantages of the method of stepping the selection switches AS, BS etc., so that they take two steps for each complete received impulse, lies in the spacing between outlets which results. Odd bank terminals only are used so that the chance of a short circuit occurring between two adjacent close contactors, say, is considerably reduced as there is a dead terminal between them.

Lockout On signalling systems using a single channel over which signals may be transmitted in either direction but not simultaneously in both directions, provision must be made to prevent a sender from interfering with received signals. provision is illustrated in the accompanying drawings. At the control station the indication receiver is shown in suflicient detail, to enable a proper understanding of same. The receiver in Fig. 1 comprises a pair of polarize; relays I? and IN, similar to relays I? and IN of Fig. 2. The armature of relay llil is connected to a positive sou cc and applies a potential to relay G either over the front contact of IN or the back contact of IN, armature of rela 1? back contact of IP'. Contact Gi connects positive voltage to relay C. The armature of relay C is connected to the front contact of relay 1? and delivers a positive potential to relay QST over TLZE, wiper arm CS2, relay CST, negative. Relays 1N and 11 are serially co nected and are placed across the line connecting the control station with the substations over L2, IN, 1?, hack, 0e22, Li. Thus, when relay C is energized, starting positive potential to relay CST is prevented until the final release of IN or IP, "iereby effectively locking out the sender shown in Fig. 1. At the substation the indication sender is also shown in block form, its starting circuit being via the wire labelled lockout, is in. all respects identical in structure and function with the sender shown in detail in 1. the moment relay IN operates on the seize pulse to the final release of IN or I? after g--out relay 0 having released during this period, positive is disconnected from the lookout wire so that the sender cannot start.

On the other hand, will be seen from Fig. 1 that the connection from Li to the indication receiver leads over the hack contacts (313(2) and CSACE) Even if CD is not energized, the indication receiver will remain inoperative during inpulse transmission since contact (IRAQ) will not remain closed for sufficiently long periocs to permit energization, by the seize pulse, of the slowacting receiving relay corresponding to relay G of Fig. 2. An analogous arrangement is provided for the indication sender of Fig. 2, shown in the form of a switch in series with wire Ll.

What is claimed is:

1. An electric Signalling system for designating any one of a plurality of units to be operated, each of which units is identifiable by a separate three digit code number, comprising a first multi-bankswitch having preselectable contacts representative of respective pieces of apparatus to be controlled, a second multi-bank switch having a normal and a plurality of oil-normal contacts, a transmission line, and means for applying to said transmission line a series of impulse trains of divers polarities and duration characteristic of the position of said first switch, said means including an impulse generator, a manually closable starting circuit for said generator, means for stepping said second switch in synchronism with said generator, means under the control of said generator for repeatedly applying a signalling potential to said line, a relay for reversing the polarity of said signalling potential, and applying a pulse of longer duration than the preceding ones and an energizing circuit for said relay which includes a wiper and off-normal contact of said second switch and a wiper and preselected contact of said first switch.

2. A system as set forth in claim 1, wherein said first means further comprise a relay for restoring the polarity of said signalling potential, and an energizing circuit for said restoring relay which includes a wiper and off-normal contact of said second switch and a wiper and preselected contact of said first switch.

3. A system as set forth in claim 1, wherein said first means further comprise a relay for restoring the polarity of said signalling potential, and wherein said starting circuit includes a pair of alternatively operable keys, one of said keys being adapted to inactivate one of the said relays in a predetermined oil-normal position of said second switch.

4. A system as set forth in claim 1, wherein the means for applying a signalling potential to the transmission line include an interrupter contact operable in synchronism with said impulse generator, and wherein means is provided for bridging said interrupter contact in certain positions of said second switch.

ERIC MALCOLM SWIFT MCWHIRTER. HAROLD MOUNTJOY MUSCHAMP DASSIS-FONSECA. HUGH JENNINGS WARD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,790,866 Hudd Feb. 3, 1931 1,960,779 Hershey May 29, 1934 1,976,398 Hoover Oct. 9, 1934 2,053,749 Steeneck Sept. 8, 1936 2,135,794 Burns Nov. 8, 1938 2,140,138 Miller Dec. 13, 1938 2,381,499 Jackel Aug. 7, 1945 2,393,377 J ackel Jan. 22, 1946 

